1. Field of the Invention
This invention relates generally to valves for dispersing a fluid into a flowing liquid stream; and, more particularly to a check valve system for intimately admixing an amount of a fluidic substance into a flowing stream.
2. Related Art
Valves for dispersing a fluid into a flowing liquid stream are well known. The typical operation of these valves involve a remote operator or automated controller that opens and closes the valves through an actuator. Common actuators include knobs, cranks, solenoids, motors and the like. Gate valves and ball valves are particularly well suited to being turned on and shut off by an actuator. Unfortunately, these valves usually remain open for at least a short time after they have finished dispersing fluid, and the flowing liquid stream backflows into the valve feed lines. This backflow commonly results in the premature corrosion of the valve and unwanted contamination of the dispersing fluid.
One type of valve which automatically shuts to prevent backflow is, a so called, check valve. These valves are opened by the fluidic pressure of the fluid flowing through the valve assembly, usually against a constant force, such that when the opening pressure is terminated, the valve automatically shuts to prevent inadvertent leakage or mixing of the flowing fluid with the fluid to be distributed through the valve. Such valves are particularly useful for protecting an ecosystem where failure to maintain flow could allow back seepage into, for example, a reservoir, causing contamination. This is especially important with chemicals, sewage systems, portable water systems and the like. In many systems, especially aqueous systems, chemicals and other substances which can be highly toxic and sometimes highly insoluble in the aqueous stream are required to be mixed at a fairly high rate requiring the intimate dispersion of the substance flowing through the valve within the flowing stream to afford an even distribution and therefore admixing of the substance with the flowing stream. In these applications the valve configuration is particularly important.
One application of the valve is for adding agrochemicals to farmlands. This procedure has come to be known as chemigation and involves the introduction of agriculturally based chemicals into irrigation water to provide for intimate admixing of the chemicals and the irrigation water stream such that the subsequent dispersion of the irrigation water carries, well admixed therein, the agrochemicals onto the cropland. Chemicals such as fertilizers, insecticide, pesticides, herbicides, fungicides, etc., can be dispersed by this method in order to be effective. Such chemicals must be well dispersed in the irrigation water prior to the water being sprayed upon the cropland. Care must be taken in order to assure that in the event of a shutdown in the flow of irrigation water, the chemical will not flow into the water source causing contamination of the source of water. Also, it is necessary that irrigation water does not flow into the chemical supply system causing overflow and area contamination.
Although some agricultural chemicals are soluble in water, it is also desirable to effectively disperse chemicals which are not readily soluble or are insoluble in water. These chemicals are often dissolved in solvents such as kerosene which is water insoluble. Certain chemicals, such as fertilizers, are available as a slurry of solids in a liquid. Therefore, it is desirable to effectively disperse a water insoluble (or minimally soluble) material into a stream of irrigation water. Such a process requires production of small droplets or micelle like moieties of the substance proximate a current in the stream to intimately admix the substance in the irrigation water stream. The traditional gate valve or even the ball check valve do not posses the dynamics required to effect thorough, intimate admixing required. Even center posted flexible mixing valves lack the structure to provide the required mixing dynamics.
In addition to the need to disperse such agrochemicals in the large scale agri-industry, there is also a need to disperse chemicals in semi-commercial and domestic arenas. For example, golf courses, athletic fields, public parks and the like require fertilization, and control of unwanted vegetation, such as weeds. The irrigation system of choice for these applications is the "pop up" type head sprinkler systems. By the use of the above referenced dispersion techniques for placing herbicides, pesticides, and fertilizers directly into existing sprinkler systems, hundreds of thousands of dollars a year can be saved. Thus, golf greens, parkways, fairways, soccer, football and baseball fields, and public parks could be fertilized and otherwise treated by application of these chemicals through a pre-existing sprinkler system. However, in this application the dispersion mechanism must provide for very minute adjustments because the amount of water applied is significantly reduced from the standard type agricultural application. Likewise, in the domestic market the ability to simultaneously fertilize, apply insecticides, herbicides and the like through domestic sprinkler systems would be very desirable.
In addition to the agricultural industry, fluid dispersing valves find use in the petrochemical industry and other manufacturing processes, such as the food and beverage industry, where the intimate admixing of one fluid, liquid or gas into one or more fluids, liquids or gases is necessary. Such fluid dispersal can involve highly toxic or corrosive chemicals, and chemicals to be admixed at temperatures elevated or depressed from typical room temperatures. These applications require a dispersal valve which can function reliably in chemically hostile environments without the need for frequent cleaning of the valve causing significant downtime in the refining or manufacturing process.
Although there are many valves in the art, including check valves, they all suffer from one or more drawbacks which make them less than desirable, especially in maintenance free applications. Since the valve must be inserted directly into the flowing stream, they are hidden from view. This makes a maintenance free, simple system a must. This is especially true for domestic applications. The major drawback with the prior art valves is that they tend to clog or jam by buildup of chemicals not dispersed into the flowing stream. To remove any chemical buildup, the valve and the valve mechanism have to be continually "cleansed" with a portion of the flowing stream. Additionally, since many of the chemicals are marginally water soluble, as the valve opened, large amounts of undispersed material are released into the stream.
Examples of prior art valves are the Raguse valve sold under the trade name ShurMix In-Stream.TM. by Raguse & Co., Inc., P.O. Box 470507, Tulsa, Okla. 74147-0507. This valve is a ball valve designed such that as the ball is raised from the valve seat by the pressure of the fluid to be dispersed, the dispersion pattern becomes conical in shape flowing up and around the ball. The material is not forced outwardly into the flowing stream to intimately admix the chemical substance with the flowing stream. Additionally, the valve spring used to tension the ball in the valve seat has to be continually cleansed.
In order to overcome the disadvantage of the ball valve, a flat seated valve is disclosed in U.S. Pat. No. 4,715,393. This valve places all the operating parts of the check valve in the flowing stream to provide uniform and rapid dispersion of the fluid as well as a cleansing of the check valve mechanism to prevent jamming, sticking or the like. This flat valve then provides a radial dispersion pattern of the fluid parallel to the flowing stream as opposed to a conical dispersion pattern of the ball valve. The radial dispersion pattern provides for more intimate admixing of the fluidic substances into the flowing stream, while simultaneously preventing the clogging or jamming of the valve mechanism.
Savage, U.S. Pat. No. 3,267,959, discloses a valve which is said to function as an anti-fouling and anti-siphoning valve in irrigation systems. The valve is provided with a neck portion which is designed to extend into the flowing stream being treated so that the chemicals being discharged will be "immediately absorbed by the liquid and removed from the position of the valve proper." The valve is designed to open when the chemical being injected is subjected to pressure equal to, or greater than, the sum of the pressure of the fluid flowing in the pipe into which the valve extends. An array of slots is provided in the tip portion so that when the chemical flows past the O-ring seal the chemical can disperse through the slots thereby providing an early release of discharge pressure to avoid dislodging the O-ring seal. This valve has a significant disadvantage in that, when the flow rate of the chemical is increased and the valve member containing the O-ring travels past the end of the housing containing the slots, the valve stem can be subjected to a significant lateral force by the flow of the liquid stream past the valve. This lateral force can bend the valve stem resulting in failure of the O-ring valve to seat properly. Deflection of the extended valve stem can also result in the valve jamming open. Either effect will allow the chemical to continue to leak into the system, or allow liquid in the conduit to pass through the check valve back to the source of the chemical.
Gilroy, U.S. Pat. No. 4,437,611 (1984), discloses a spray nozzle to be used in a sprinkler system in a corrosive or dirty environment. The spray nozzle is designed to be mounted in a conduit wall essentially flush with the method and apparatus for dispersing substantially water soluble agricultural chemicals into an irrigation system. This method involves dispersing the chemical by passing a pressured stream containing the chemical through an orifice. The dispersed stream passes through a check valve and subsequently through an entry line which projects into the water stream. This procedure has the disadvantage of requiring a substantial amount of additional equipment in order to effectively disperse the chemical into a stream which must then be dispersed into the main irrigation stream.
U.S. Pat. No. 3,693,656 to Sauer discloses a solution mixing apparatus for insertion into a flowing stream parallel to the flow. Anchoring the valve assembly requires a mounting structure interior the conduit carrying the flowing stream. The valve body terminates in a frustra conical cavity covered by a longitudinal flexing disk centrally anchored to the valve body by a center post. Upon sufficient pressure from a fluid inside the first conduit, the periphery of the disk is forced away from valve body at the mouth of the cavity in a "flapping" motion causing the first fluid to flow into a second fluid which is flowing inside the second conduit. This apparatus does not provide a flat valve seat perpendicular to the pressured flow of the first fluid. Therefore, the first fluid does not impinge the flat surface of the valve but rather "seeps" or "squirts out" along the interface between the edge of the frustra conical cavity and the periphery of the resilient disk. In addition the frustra conical cavity is positioned interior the valve body such that fluid can settle in the dead space in this small cavity causing clogging, this is especially true for suspensions and/or emulsions. Finally, because the disk is required to flex longitudinally, this device is inoperative if a solid-non flexible, anti-corrosion shield or valve piece is required to cover the disk when for example, a highly corrosive material is required to be mixed.
U.S. Pat. No. 3,464,626 (1969) to Stamps et al is a continuation-in-part of U.S. Pat. No. 3,375,976 (1968) which is a continuation-in-part of U.S. Pat. No. 3,326,232 (1967). U.S. Pat. No. 3,464,626 discloses a process and apparatus for evenly applying highly water insoluble agricultural chemicals to farmland at variable intensities. The process and apparatus continually agitates a suspension of the insoluble chemical before it passes through a flow meter, a control valve, an orifice plate, a check valve, and finally through a nipple placed in the center of the diameter of the irrigation pipe to be distributed over the farmland in the irrigation water. There is a pressure drop across the control valve and the orifice which serves to keep the insoluble chemical in suspension long enough to disperse the suspension into the irrigation water through the nipple and distribute the chemical evenly over the farmland with the irrigation water. In the disclosed process and apparatus, the check valve and nipple are separated by a length of transparent pipe in order to allow the operator to visually inspect the check valve for jamming and clogging by the chemical. When the check valve does jam or clog, the transparent pipe is removed so the valve may be cleaned. This process and apparatus for applying water insoluble agricultural chemicals to farmland does not immerse the check valve in the flowing stream of irrigation water, which makes the check valve vulnerable to jamming and clogging by buildup of the chemical.